Improved high-pressure liquid chromatographic method for the analysis of erythromycin in solid dosage forms

Area of Science:

• Analytical Chemistry
• Pharmaceutical Analysis

Background:

• Accurate quantification of erythromycin in pharmaceutical formulations is crucial for ensuring therapeutic efficacy.
• Developing stability-indicating methods is essential for assessing drug degradation and shelf-life.

Purpose of the Study:

• To develop and validate a stability-indicating high-performance liquid chromatography (HPLC) method for the assay of erythromycin in enteric film-coated tablets.
• To evaluate the method's applicability for analyzing erythromycin salts and esters.
• To compare the HPLC assay results with a microbiological assay for bioequivalency.

Main Methods:

• Utilized a reversed-phase HPLC system with a specific mobile phase composition (acetonitrile-methanol-0.2 M ammonium acetate-water at pH 7.0) and column temperature (70°C).
• Validated linearity and precision by spiking erythromycin into a tablet placebo across a range of 60-120% of label claim.
• Determined correction factors for erythromycins A, B, and C to express results in terms of antimicrobial bioequivalency against *Staphylococcus aureus*.

Main Results:

• The developed HPLC method demonstrated high recovery (99.9%) and precision (RSD < 1%) for erythromycin assay in solid dosage forms.
• The method proved applicable for analyzing various forms of erythromycin, including salts and esters.
• Assay results from eight tablet lots using the HPLC method showed no statistically significant difference compared to microbiological assay results when expressed as erythromycin bioequivalency.

Conclusions:

• A robust and validated stability-indicating HPLC method for erythromycin assay in enteric film-coated tablets has been established.
• The HPLC method provides accurate and reliable quantification, comparable to traditional microbiological assays for determining erythromycin bioequivalency.
• This validated HPLC method can be effectively employed for routine quality control and stability testing of erythromycin formulations.